Liquid level detection devices are known in the art. For example, U.S. Pat. No. 5,775,164 discloses a device for detecting the level of a liquid in a container. This particular device comprises two electrodes that are arranged in the container and an electronic circuit that is connected to the electrodes. In order to prevent the measuring voltages from electrolyzing the liquid, an a.c. voltage is only generated between the electrodes during brief measuring phases in order to measure the electric resistance between the electrodes.